The present invention relates to a high-frequency incision instrument for an endoscope, to be inserted through an instrument insertion channel of the endoscope for executing an endoscopic mucosal resection (EMR) and other procedures.
Operational procedures adopted in the endoscopic mucosal resection include injecting physiological saline solution under a mucous membrane to be resected to thereby bulge the portion thereof to be resected, and incising the base portion of the bulge in a horizontal direction, with the high-frequency incision instrument.
For such purpose, a high-frequency incision instrument for an endoscope with a high-frequency electrode exposed along a side of a distal portion of an insulative flexible sheath, such as the one disclosed in Japanese Utility Model Publication No. SHO 61-7694, has been suitably employed.
FIG. 9 illustrates a process of the endoscopic mucosal resection with a high-frequency incision instrument for an endoscope. A tip portion of a flexible sheath 1 projecting into a body cavity through an instrument insertion channel of the endoscope (not shown) is horizontally moved by manipulation of the endoscope, so as to resect a base portion of a bulge 100 of a mucous membrane with a wire-shaped high-frequency electrode 2, through which a high-frequency current is supplied.
The high-frequency electrode 2 is disposed along an outer surface of the flexible sheath 1 between a pair of through holes 4A, 4B perforated on a lateral surface close to the tip portion of the flexible sheath 1, and connected to a conductive operating wire (not shown) inserted through the flexible sheath 1.
When thus performing the endoscopic mucosal resection, in the case where the bulge 100 to be resected is larger than the high-frequency electrode 2 as shown in FIG. 9, it is impossible to completely resect the bulge 100 by a single resecting action, and hence the resecting action has to be repeated several times.
However, the flexible sheath 1 is interfered with by the bulge 100 on its way back to the initial position, after partially resecting the bulge 100, for performing the next resection. Accordingly, the endoscope has to be operated to move the flexible sheath 1 so as to avoid the interference with the bulge 100, which incurs considerable trouble in accurately setting the flexible sheath 1 on the initial position for the next incision.
To minimize such trouble, inverting the orientation of the high-frequency electrode 2, as shown in FIG. 10, by rotating only the tip portion of the flexible sheath 1 to which the high-frequency electrode 2 is attached, around an axial line thereof through a manipulation by hand, enables quickly setting the flexible sheath 1 on the initial position for the next incision. This invention has already been applied for a patent, under Japanese Patent Application No. 2004-152632, which has now been published as Japanese Patent Provisional Publication No. 2005-334000.
The flexible sheath 1 of such high-frequency incision instrument for an endoscope basically includes a short distal tube 1A to which the high-frequency electrode 2 is attached, loosely inserted so as to rotate around the axial line, into a tip portion of a long proximal tube 1B, larger (or smaller) in diameter than the distal tube 1A and extending to reach the operator.
Meanwhile, upon supplying the high-frequency current to the high-frequency electrode 2 thus to perform the mucosal resection, during the use of the high-frequency incision instrument for an endoscope, burnt residuum may splash around thereby disturbing the endoscopic observation for confirming the position to be resected next. In such case, as indicated by arrows W in FIG. 11, irrigation water has to be injected from the through holes 4A, 4B (or an independently provided water injection outlet), to wash away the burnt residuum.
From such viewpoint, the foregoing flexible sheath 1 insert-connected to the mating tube of a different diameter is not capable of injecting the irrigation water, because, as indicated by arrows W in FIG. 12, the irrigation water leaks out forward through the joint portion between the sheath and the tube.
Attaching a sealing material such as an O-ring to the joint portion may prevent the leakage, however providing the O-ring incurs frictional resistance at the joint portion, which inhibits smoothly rotating the distal tube 1A to which the high-frequency electrode is attached by manipulation of the flexible sheath 1 by hand, because the flexible sheath 1 is not only flexible but as slender as only approx. 2 mm in diameter over a length of 1 to 2 m.